JP2009194783A - Pattern antenna and antenna apparatus with pattern antenna mounted on master substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure excellent antenna characteristics even when a substrate is small-sized. <P>SOLUTION: In a pattern antenna 1 where an F-shaped antenna element 3 and a GND region 4 are pattern-formed on a printed circuit board 2, if a substrate width L of the substrate 2 is made smaller than 1/4 frequency to be used, a wiring width B of a short-circuiting part 3b linking the antenna element 3 to the GND region 4 is made larger than a wiring width A of a long-axis part 3a of the antenna element 3. By adjusting the wiring width B of the short-circuit part 3b in such a direction as being greater than the wiring width A of the long-axis part 3a, input impedance is changed. Thus, mismatching of impedance caused by reducing the substrate width L of the substrate 2 is adjusted and excellent antenna characteristics are ensured, wherein it is preferable that the wiring width of the short-circuit part 3b is 4 times or more as large as the wiring width of the long-axis part 3a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pattern antenna and an antenna device in which the pattern antenna is mounted on a parent substrate, and more particularly to a pattern antenna or the like in which an F-type antenna element is patterned on a substrate.

  Conventionally, F-type antennas have been widely used as small wireless antennas for cellular phones and personal computer communications. As this type of F-type antenna, an antenna element or the like formed on a dielectric substrate in a pattern is known. For example, Patent Document 1 discloses an electric circuit of a ground conductor plate (hereinafter referred to as “GND region”). There has been proposed an F-type antenna in which the length is formed to be about ¼ of the operating frequency so as to obtain good SWR characteristics.

  FIG. 10 is a top view showing the configuration of the pattern antenna described in the above document. This pattern antenna 51 is roughly divided into a printed circuit board 52 and an F-type antenna element 53 patterned on the surface of the circuit board 52. And a GND region 54 formed on the back surface of the substrate 52. A through hole 56 is provided at the tip of one wiring (short-circuit line) 55 extending from the antenna element 53, and the antenna element 53 and the GND region 54 are electrically connected through the through hole 56. The other wiring 57 extending from the antenna element 53 is a power supply wiring, and other electronic devices are connected to the power supply wiring 57.

  In the pattern antenna 51, the current distribution value of the antenna element 53 and the current distribution value of the GND region 54 at the feeding point are set by setting the length GL of the GND region 54 to about ¼ of the use frequency. And stable antenna characteristics are obtained.

JP 2001-168629 A

  However, in the conventional pattern antenna 51, since the length GL of the GND region 54 needs to be about ¼ wavelength in order to obtain optimum antenna characteristics, the substrate width BL of the printed circuit board 52 (see FIG. 10). ) Also has to be secured, and there is a problem that miniaturization of the substrate 52 is limited. In particular, in the pattern antenna 51, when the length GL is shorter than ¼ wavelength, impedance mismatch occurs, so that the antenna gain characteristic is lowered, and good antenna characteristic may not be ensured.

  The pattern antenna 51 is used not only when the antenna is used alone, but also by being mounted on a large mother board 62 (GND potential) via a connector 61 as shown in FIG. In some cases. However, in this case, even if there is no problem as long as it is used alone, the antenna gain characteristics may deteriorate or the center frequency may fluctuate greatly when mounted on the parent board. For this reason, there is a problem that the use mode of the pattern antenna is limited or a separate design for mounting on the parent substrate is required.

  Accordingly, the present invention has been made in view of the above-described problems in the prior art, and an object thereof is to provide a pattern antenna capable of reducing the size of a substrate while ensuring good antenna characteristics. And

  Another object of the present invention is to prevent the antenna gain characteristic from deteriorating or the center frequency to fluctuate greatly even when the pattern antenna is mounted on the parent board, thereby ensuring good antenna characteristics. Is to provide a simple antenna device.

  In order to achieve the above object, the present invention provides a pattern antenna in which an F-type antenna element and a grounding region are patterned on a substrate, wherein the substrate width of the substrate is smaller than a quarter wavelength of the operating frequency, and the antenna element The wiring width of the short-circuit portion that connects to the ground region is larger than the wiring width of the long axis portion of the antenna element.

  In the present invention, the input impedance is changed by adjusting the wiring width of the short-circuit portion to be larger than the wiring width of the long axis portion, thereby reducing the impedance generated by reducing the substrate width of the substrate. Adjust the mismatch and ensure good antenna characteristics.

  In the pattern antenna, the wiring width of the short-circuit portion can be set to a size that is four times or more the wiring width of the long axis portion.

  The said pattern antenna can be comprised so that it may have a bending part in the open end side of the said antenna element. At this time, it is preferable that the bent portion has a non-cornered shape.

  In the pattern antenna, the antenna element and at least a part of the grounding region are formed on the same surface of the substrate, are continuous with the long axis portion, and are disposed at positions facing the long axis portion. And at least a part of the grounding region can be set to be twice or more the wiring width of the long axis portion.

  The present invention is also an antenna device in which a F-type antenna element and a pattern antenna in which a grounding area is formed on a substrate are mounted on a parent substrate, and the substrate of the pattern antenna is orthogonal to the long axis portion of the antenna element. The ratio of the substrate width in the direction to be parallel to the substrate width in the direction parallel to the long axis portion is 1.3 or more and 2.1 or less.

  In the antenna device, a ratio of the width of the antenna element arrangement region to the width of the ground region in a direction orthogonal to the long axis portion of the antenna element can be 0.14 or more and 0.22 or less.

  In the antenna device, a metal case fixed to a ground potential and covering a circuit element on the front or back surface may be provided on the front or back surface of the pattern antenna.

  As described above, according to the present invention, it is possible to provide a pattern antenna capable of reducing the size of a substrate while ensuring good antenna characteristics. In addition, according to the present invention, even when the antenna substrate is mounted on the parent substrate, the antenna gain characteristics are prevented from being lowered and the center frequency is not greatly changed, and an antenna capable of ensuring good antenna characteristics. An apparatus can be provided.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing an embodiment of a pattern antenna according to the present invention, and (a) and (b) are a front view and a back view, respectively.

  As shown in the figure, the pattern antenna 1 is roughly divided into a printed circuit board 2 (hereinafter abbreviated as “substrate”), an antenna element 3 and a GND region 4 patterned on the surface of the substrate 2, and the substrate 2. It is comprised from the electric power feeding wiring 5 patterned in the back surface.

  The substrate 2 is a dielectric substrate formed of, for example, glass epoxy, and in the present embodiment, the substrate width L of the substrate 2 is formed to be shorter than a quarter wavelength of the use frequency.

  The antenna element 3 is an F-type antenna element, a long shaft portion 3a extending along the short side direction of the substrate 2, a short-circuit portion 3b connecting the long shaft portion 3a and the GND region 4, and a long shaft portion 3a And a power feeding section 3c for connecting the power feeding wiring 5.

  In the present embodiment, the wiring width B of the short-circuit portion 3b is formed larger than the wiring portion A of the long shaft portion 3a, and this point is greatly different from the conventional antenna. That is, instead of setting the wiring width of the long axis portion and the wiring width of the short-circuit portion to substantially the same size as in the conventional antenna (see, for example, the pattern antenna 51 in FIG. 10), the short-circuit portion By expanding the wiring width B of 3b in the short direction of the substrate 2, the antenna characteristics can be adjusted, and thereby the GND region 4 can be reduced in size.

  Specifically, when the wiring width B of the short-circuit portion 3b is increased, the inductance component on the GND side viewed from the feeding point G can be reduced, and thereby the input impedance can be adjusted. As described above, when the substrate width L of the substrate 2 (the length of the side parallel to the long axis portion 3a of the antenna element 3) is smaller than ¼ wavelength, mismatching of the input impedance occurs as described above. By compensating the collapse to some extent by adjusting the input impedance by increasing the wiring width B, the substrate width L can be reduced without impairing the antenna gain characteristics.

  In this case, if the wiring width B is too small, the adjustment width of the input impedance is narrowed and may not contribute to the overall impedance matching. Therefore, the size of the wiring width B is the wiring width of the long shaft portion 3a. It is preferable to be 4 times or more of A. It should be noted that the size of the wiring width B can be set to the same level in any band as long as the use band is 2.0 to 3.0 GHz. However, if the wiring width B is too large, the area occupied by the short-circuit portion 3b increases, which may lead to an increase in the size of the substrate 2, which is not preferable.

  On the other hand, a bent portion 3d is formed on the open end side of the antenna element 3, thereby securing an antenna wiring length of about ¼ wavelength. The bent portion 3d is preferably formed in a U shape by performing a corner circular process in order to reduce the number of reflection points, but may be formed in other shapes such as a U shape.

  When the bent portion 3d is formed, a wiring portion (hereinafter referred to as “open portion”) 3e facing the long shaft portion 3a is positioned in the vicinity of the GND region 4. In this case, since the open part 3e has a capacity and may affect the antenna resonance frequency, the distance C between the open part 3e and the GND region 4 is more than twice the wiring width A of the long shaft part 3a. It is preferable to set to a low degree of coupling.

  Further, a through hole 6 is provided at the tip of the power feeding portion 3 c of the antenna element 3, and the antenna element 3 and the power feeding wiring 5 on the back surface of the substrate are electrically connected through the through hole 6. The power supply wiring 5 can be an impedance matched microstrip line, strip line, coplanar line, or the like. It is also possible to attach a coaxial wiring on the substrate 2 and perform power feeding.

  2A shows the S11 reflection characteristic from the feeding point G in the pattern antenna 1 shown in FIG. 1, and FIG. 2B shows the S11 Smith chart. In the actual measurement of the antenna characteristics, the wiring width B of the short-circuit portion 3b is set to four times the wiring width A of the long shaft portion 3a, and the substrate width L of the substrate 2 is set to about half the quarter wavelength. . Further, the pattern antenna 1 has a resonance point in the vicinity of 2.4 GHz by adjusting the position of the feeding part 3c (position of the feeding point G) and the length D of the opening part 3e (see FIG. 1A). The antenna was designed so as to obtain the highest antenna radiation characteristics in the same band.

  As can be seen from the figure, assuming that a bandwidth of about 100 MHz is required as a use band, both the resonance point and the radiation characteristic are obtained, and according to the present embodiment, the substrate 2 It can be seen that good antenna characteristics can be secured even if the substrate width L is reduced to about half the quarter wavelength.

  FIG. 3 shows the radiation characteristics of the pattern antenna 1. The waveform is an antenna directivity pattern rotated about the vertical axis with respect to the substrate plane of the antenna substrate, and shows characteristics with respect to vertical polarization and horizontal polarization. As can be seen from the figure, the pattern antenna 1 is omnidirectional with respect to the antenna element 3 and has good radiation characteristics.

  Next, a method for manufacturing the pattern antenna 1 shown in FIG. 1 will be described. In manufacturing the pattern antenna 1, an organic substrate or a ceramic substrate is prepared, and the antenna element 3, the GND region 4, and the like are formed on the pattern.

  In the above case, the substrate 2 can be a single-layer substrate, a double-sided substrate, a multilayer substrate, or the like. In addition, as the material of the substrate 2, various materials such as a low dielectric loss tangent substrate material having a high high frequency loss and a high dielectric substrate material can be used. In this case, the wavelength shortening rate corresponding to each dielectric constant is considered. It is necessary to adjust the antenna design.

  On the other hand, as a pattern forming method, a mask printing process used for a ceramic substrate, a pattern forming process using etching used for a printed board, a pattern forming process using vapor deposition used for a semiconductor process, or the like can be used. When the substrate 2 is formed of a multilayer substrate, the antenna element 3 and the GND region 4 can be formed in the inner layer of the substrate 2 (between the upper layer substrate and the lower layer substrate).

  Next, another embodiment of the pattern antenna according to the present invention will be described with reference to FIG. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in the figure, the pattern antenna 20 has the same basic configuration as that of the pattern antenna 1 shown in FIG. 1, but a part of the GND region 4 (GND region 21) is different from the back side of the substrate 2 (different from the antenna element 3). Layer). In this pattern antenna 20, a GND region 4 formed on the front surface side of the substrate 2 and a GND region 21 formed on the back surface side of the substrate 2 are connected via a GND through hole 22.

  In the pattern antenna 20, since the GND area is configured by dividing the front surface and the back surface of the substrate 2, a circuit element (not shown) such as a transmission circuit may be formed in the empty area 23 secured below the GND area 4. Even when the circuit element is formed on the back surface side of the substrate 2, it can be formed on the GND region 21. Thus, since the circuit element can be mounted on either the front surface or the back surface of the substrate 2, the length of the power supply wiring to the antenna element 3 can be shortened, and the transmission loss can be reduced.

  Next, an embodiment of an antenna device according to the present invention will be described.

  FIG. 5A shows the S11 reflection characteristics of the conventional pattern antenna 51 shown in FIG. 10, and FIG. 5B shows the S11 Smith chart. FIG. 6A shows S11 reflection characteristics when the F-type antenna 51 is mounted on the parent substrate 62 (GND potential) as shown in FIG. 11, and FIG. 6B shows the same configuration. S11 Smith chart is shown. The pattern antenna 51 is designed so that the substrate width BL (see FIG. 10) of the substrate 52 is ¼ wavelength and designed to have a resonance point in the vicinity of 2.4 GHz.

  As can be seen from FIG. 5, the conventional antenna shows excellent antenna characteristics when used as a single pattern antenna, but as shown in FIG. 6, when the pattern antenna is mounted on a parent board, It can be seen that the resonance frequency and impedance matching vary greatly. As described above, in the conventional antenna device, there is a problem that the antenna gain characteristic is greatly reduced when mounted on the parent substrate, and it is difficult to ensure stable antenna characteristics.

  Therefore, in the antenna device according to the present embodiment, by adjusting various dimensional ratios of the pattern antenna substrate, antenna element, and GND region, the pattern antenna is used alone, and the pattern antenna is mounted on the parent substrate. In any case, good antenna characteristics can be ensured.

  FIG. 7A is an overall view showing the antenna device according to the present embodiment, and FIG. 7B is an enlarged view of a region 40 in FIG. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 1A, an antenna device 30 includes a pattern antenna 31 in which an antenna element 3 and a GND region 4 are patterned, and a parent substrate 32 connected to the pattern antenna 31 via a connector 33 for connection. It consists of. Circuit elements (not shown) such as a transmission circuit and a reception circuit are formed on the surface of the parent substrate 32, and these circuit elements are connected to the pattern antenna 31 through the connection connector 33.

  In the present embodiment, as shown in FIG. 7B, in the substrate 35 of the pattern antenna 31, the substrate width E in the direction orthogonal to the long axis portion 3a of the antenna element 3 and the direction parallel to the long axis portion 3a The ratio with respect to the substrate width F is set to 1.3 to 2.1. At this time, the ratio between the width H of the arrangement region of the antenna element 3 and the width J of the GND region 4 in the longitudinal direction of the substrate 35 is 0.14 to 0.22 after satisfying the above conditions. It is more preferable to set. As shown in FIG. 4, when the GND region 4 is provided on the front and back surfaces of the substrate 35, the width J of the GND region 4 is equal to the width of the GND region formed on the surface of the substrate 35. The total value obtained by adding the widths of the GND regions formed on the back surface of the substrate 35 is obtained by subtracting the width of the region overlapping the GND regions on the front and back surfaces.

  FIG. 8A shows the S11 reflection characteristics of the antenna device 30 shown in FIG. 7, and FIG. 8B shows the S11 Smith chart. In the actual measurement of the antenna characteristics, the ratio of the substrate width E in the longitudinal direction of the substrate 35 to the substrate width F in the short direction is 1.7, and the width H of the arrangement area of the antenna element 3 and the width of the GND area 4 The ratio with J was 0.18. The pattern antenna 31 was designed to have a substrate width F that is about a half of a quarter wavelength and to have a resonance point in the vicinity of 2.4 GHz. On the other hand, as the parent substrate 32, a square substrate was used, and one having a side length K approximately 3.5 times the substrate width E in the longitudinal direction of the substrate 35 was used.

  As can be seen from the figure, even when the pattern antenna 31 is mounted on the large mother board 32, the resonance occurs in the vicinity of 2.4 GHz similarly to the characteristics (see FIG. 2) when the pattern antenna 31 is used alone. In addition, the highest antenna radiation characteristics are obtained in the vicinity of 2.4 GHz. From these results, it can be seen that when the pattern antenna 31 is designed so as to satisfy the above conditions, good antenna characteristics can be secured even when the pattern antenna 31 is mounted on the parent substrate 32. In addition, compared with the characteristics when the pattern antenna 31 is used alone (see FIG. 2), there is a shift of the center frequency of about 30 MHz. However, as the bandwidth of the antenna gain, sufficient radiation performance in a wide band is obtained. Because it satisfies, there is no impact on practical use.

  Further, in the above embodiment, as shown in FIG. 9, the metal case 42 shared with the GND potential of the pattern antenna 31 is disposed on the back surface of the substrate 35 of the pattern antenna 31 to cover the circuit element. The influence of the parent substrate 32 can be further reduced. Here, the potential of the metal case 42 can be made common by connecting the metal case 42 directly to the parent substrate 32 or by connecting the metal case 42 to the GND region 4 of the pattern antenna 31.

  With the above configuration, an unnecessary resonance state between the pattern antenna 31 and the parent substrate 32 can be prevented, and more stable antenna characteristics can be obtained. In addition, in order to assist the mechanical strength between the pattern antenna 31 and the parent board | substrate 32, it is preferable that the height M of the metal case 42 is a height which fills those space | intervals.

  In addition, a metal case 42 can be provided on the surface of the substrate 35 of the pattern antenna 31. In this case, substantially the same characteristics as those shown in FIG. 9 can be realized. Note that the height M when the metal case 42 is provided on the surface side of the substrate 35 is sufficient if the height that can cover the circuit element is secured.

It is a figure which shows one Embodiment of the pattern antenna concerning this invention, (a) is a front view, (b) is a back view. It is a figure which shows the S11 reflection characteristic and S11 Smith chart of the pattern antenna of FIG. It is a figure which shows the antenna directivity of the pattern antenna of FIG. It is a figure which shows other embodiment of the pattern antenna concerning this invention, Comprising: (a) is a front view, (b) is a back view. It is a figure which shows the S11 reflection characteristic and S11 Smith chart at the time of using the conventional pattern antenna alone. It is a figure which shows the S11 reflection characteristic and S11 Smith chart at the time of mounting the conventional pattern antenna on a parent board | substrate. It is a figure which shows one Embodiment of the antenna device concerning this invention. It is a figure which shows the S11 reflection characteristic and S11 Smith chart of the antenna apparatus of FIG. It is a figure which shows other embodiment of the antenna device concerning this invention. It is a figure which shows the conventional pattern antenna. It is a figure which shows the case where the conventional pattern antenna is mounted in the parent board | substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pattern antenna 2 Printed circuit board 3 Antenna element 3a Long axis part 3b Short-circuit part 3c Feed part 3d Bending part 3e Open part 4 GND area | region 5 Feed wiring 6 Through hole 20 Pattern antenna 21 GND area | region 22 GND through hole 23 Empty area 30 Antenna Device 31 Pattern antenna 32 Parent board 33 Connector 35 Printed board 42 Metal case

Claims (9)

  A pattern antenna in which an F-type antenna element and a ground region are patterned on a substrate, wherein the substrate width of the substrate is smaller than ¼ wavelength of the operating frequency, and the wiring width of the short-circuit portion connecting the antenna element to the ground region Is larger than the wiring width of the long axis portion of the antenna element.   2. The pattern antenna according to claim 1, wherein the input impedance is changed by adjusting a wiring width of the short-circuit portion to be larger than a wiring width of the long axis portion.   The pattern antenna according to claim 1, wherein the wiring width of the short-circuit portion has a size that is four times or more the wiring width of the long axis portion.   The pattern antenna according to claim 1, wherein the antenna element has a bent portion on an open end side thereof.   The pattern antenna according to claim 4, wherein a shape of the bent portion is a non-angled shape. The antenna element and at least a portion of the ground region are formed on the same surface of the substrate;
The interval between the open portion that is continuous with the long shaft portion and is disposed at a position facing the long shaft portion and at least a part of the grounding region is at least twice the wiring width of the long shaft portion. The pattern antenna according to claim 4, wherein: An antenna device in which a F-type antenna element and a pattern antenna formed by patterning a ground region on a substrate are mounted on a parent substrate,
In the substrate of the pattern antenna, a ratio of a substrate width in a direction orthogonal to the long axis portion of the antenna element and a substrate width in a direction parallel to the long axis portion is 1.3 or more and 2.1 or less. An antenna device characterized by the above.   The ratio between the width of the antenna element arrangement region and the width of the grounding region in a direction orthogonal to the major axis of the antenna element is 0.14 or more and 0.22 or less. The antenna device according to 1.   The antenna device according to claim 7 or 8, further comprising a metal case fixed to a ground potential on a front surface or a back surface of the pattern antenna and covering circuit elements on the front surface or the back surface.

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